ANN ARBOR—When it comes to menstrual cramps, most young women just keep going, according to a University of Michigan study. Very overweight women and smokers, however, are at greater risk for troublesome cramps.

Sioban D. Harlow, assistant professor of epidemiology at the U-M School of Public Health, asked 165 women, ages 17-19, to keep menstrual diaries for one year in order to measure the occurrence, duration and severity of pain from menstrual cramps.

Harlow also examined the relationship between cramps and weight, smoking, drinking and physical activity. Her findings are reported in the November 1996 issue of the British Journal of Obstetrics and Gynaecology.

” Missing an activity due to cramps, though experienced occasionally by many women, was generally an infrequent occurrence during the study,” Harlow said. ” Even though 60 percent of the women reported at least one episode of severe pain, bed rest occurred in only 10 percent of the observed menstrual periods. Limitation of activity, when it occurred, generally lasted one day or less.” The median number of pain days was two days.

Harlow reported several lifestyle risk factors for menstrual cramps.

–” We discovered that very heavy women had about a 75 percent increase in their odds of having menstrual cramps. This is a new finding.”

–Current smokers had a 50 percent increase in the odds of having pain lasting more than two days.

–Drinking during an episode of menstrual cramps increased the severity and duration of the cramps.

” Maintaining a healthy lifestyle seems to be an important factor in avoiding menstrual pain,” Harlow stressed. ” Physicians should discuss the effects of drinking, smoking and obesity on menstrual pain so that patients can take steps to reduce their risks.”

Harlow also found that:

–Women who had longer menstrual cycles, such as a 35-day cycle, were more likely to have cramps than women with average cycles of 28-29 days.

–Women who started menstruating at a very early age—age 11 or younger—were somewhat more likely to have severe and longer lasting cramps.

–Sixty percent of the women reported at least one episode of severe pain during the study but only 13 percent reported severe pain more than half of their the periods.

–Physical activity seemed to have no effect one way or the other on cramps among women in this study, who tended to be moderate exercisers. ” Other studies of women athletes, however, have found a correlation between physical activity and reduced cramps,” Harlow noted.

Harlow also said that 84 percent of the women took pain medication for cramps at some point in the study.